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Title:: Temporal and Spatial Characteristics of Apparent Stress before Yunnan Tonghai M_S5.0 Earthquake in 2018

Author(s):: PENG Guanling; ZHAO Xiaoyan; LIU Zifeng; KONG Deyu; (Yunnan Earthquake Agency,Kunming 650224,Yunnan,China)

Keywords:: Tonghai M_S5.0 earthquake; apparent stress; earthquake risk; focal parameters

摘要:: 利用云南数字地震台网资料,计算了2008年1月1日至2018年8月13日,2018年云南通海M_S5.0地震震中100 km范围内3.0≤M_L<5.0地震的震源参数,得到参数间的定标律关系。为了扣除震级对视应力的影响,采用规准化视应力,获得了规准化视应力时间进程及空间分布图像。结果显示:地震视应力与震级、地震矩的皮尔逊相关系数分别为0.63,0.37,视应力与地震矩的相关性不显著; 视应力标度率特征符合区域构造特征。通海M_S5.0地震前15.6个月,视应力和规准化视应力均出现高值异常,距离震中46 km,出现高值异常区域,说明该区域高视应力值对5级以上地震具有一定指示意义。

Abstract:: Based on data of the Yunnan Digital Seismic Network,we calculated the focal parameters of 3.0≤M_L<5.0 earthquakes within a 100 km radius of the epicenter from Jan.1,2008 to Aug.13,2018,and obtained several scaling law among the parameters.In order to deduct the effect of magnitude on apparent stress,we obtain the image of temporal process and spatial distribution by using the normalized apparent stress.The results show that the Pearson correlation coefficients between apparent stress and magnitude and seismic moment are 0.63 and 0.37,respectively,which may indicate that the correlation between apparent stress and seismic moment is not significant,and the characteristics of apparent stress scale rate conform to regional tectonic characteristics.During the 15.6 months before the Tonghai M_S5.0 earthquake on Aug.13,2018,both of the apparent stress and normalized apparent stress appeared high value anomalies.The high value anomaly area appeared 46 km away from the epicenter,which indicated that the high apparent stress value in this area showed certain indication significance for the occurrence of M≥5.0 earthquakes.